M, The Malpighian or renal caecal diverticula of Scorpio.
H, Renal epithelium lining the renal sacs.
Both belong to the category of " coelomoducts," namely, r- ' tubular or funnel-like portions of the coelom opening to the exterior in pairs in each somite (potentially,) and usually persisting in only a few somites as either "urocoels" (renal organs) or "gonocoels"(genital tubes).
Certainly not all cases of renal dropsy show diminution in the excretion of chlorides.
There is no renal portal system, excepting unimportant vestiges of such a system in the head kidneys.
Close to this the small renal organ (i, mediad) and the larger renal organ (k, to the right and posteriorly) are seen, also the pericardium (1) and a coil of the intestine (int) embedded in the compact liver.
17, d), we find right and left of the two renal apertures a right and left gillplume or ctenidium, which here as in Haliotis and Pleurotornaria retain their original paired condition.
The existence of two renal organs in Patella, and their relation to the pericardium (a portion of the coelom), is important.
Each renal organ is a sac lined with glandular epithelium (ciliated cell, with concretions) communicating with the exterior by its papilla, and by ce, Cerebral ganglia.
The smaller of the two renal organs was pe, Pedal ganglion.
Time when the fact that the renal organ s,s', Nerves (right and of the Mollusca, as a rule, opens into the left) to the mantle.
Subsequent connected by nerve investigations carried on under the directo the streptoneur tion of the same naturalist have shown ous visceral loop. that the larger as well as the smaller renal sac is in communication with the pericardium.
The walls of the renal sacs are deeply plaited and thrown into ridges.
Below the surface these walls are excavated with blood-vessels, so that the sac is practically a series of blood-vessels covered with renal epithelium, and forming 6 Cephalic tentacle.
The larger renal sac (remarkably enough, that which is aborted in other FIG.
- Diagram of the two renal organs (nephridia), to show their relation to the rectum and to the pericardium.
The oesophagus leads into a remarkable stomach, plaited like the manyplies of a sheep, and after this the intestine takes a very large number of turns embedded in the yellow liver, until at last it passes between the two renal sacs to the anal papilla.
H, Renal epithelium lining the renal sacs.
Large or external or right renal organ.
Small or median renal organ.
Near this and less advanced into the branchial chamber is the single renal organ or nephridium r with its opening to the exterior r'.
The heart c lying in the pericardium is seen in close proximity to the renal organ, and consists of a single auricle receiving blood from the gill, and of a single ventricle which pumps it through the body by an anterior and posterior aorta.
Q, Renal organ (nephridium).
1, The renal sac (nephridium).
L', The ciliated communication of the renal sac with the pericardium.
M, The external opening of the renal sac.
With regard to internal organization we may commence with the disposition of the renal organ (nephridium), the external opening of which has already been noted.
The position of this opening and other features of the renal organ were determined by J.
Thus the renal organ of Aplysia is shown to conform to the Molluscan type.
Outline of part of the renal sac (nephridium) below the surface.
The typical character is retained by the heart, pericardium, and the communicating nephridium or renal organ in all Opisthobranchs.
A pair of renal tubes opening right and left, rather far forward on the sides of the body, are always present.
A pair of genital apertures, connected by genital ducts with the paired gonads, are found right and left near the nephridial pores, except in a few cases where the genital duct joins that of the renal organ (Spondylus).
It, as in other Mollusca, is not a blood-space but develops from the coelom, and it communicates with the exterior by the pair of renal tubes.
The left inner gill-plate is also snipped to show the subjacent orifices of the left renal organ x, and of the genital gland (testis or ovary) y.
The blood makes its way by large veins to a venous sinus which lies in the middle line below the heart, having the paired renal organs (nephridia) placed between it and that organ.
The pair of renal organs of Anodonta, called in Lamellibranchs the organs of Bojanus, lie below the membranous floor of the pericardium, and open into it by two well-marked apertures (e and f in fig.
The renal organs may be more ramified in other Lamellibranchs than they are in Anodonta.
From all parts of the pyriform sac narrow stalk-like tubes are given off, ending in abundant widely-spread branching glandular caeca, which form the essential renal secreting apparatus.
The glands secrete hippuric acid which passes from the pericardium into the renal organs.
In the most primitive Lamellibranchs there is no separate generative aperture but the gonads discharge into the renal cavity, as in Patella among Gastropods.
But the generative products do not pass through the whole length of the renal tube: there is a direct opening from the pericardial end of the tube to the distal end, and the ova or sperms pass through this.